This invention is directed to a harrow bearing assembly and a harrow including a bearing assembly.
Harrows are used for breaking up and levelling soil during a soil cultivation operation. One type of harrow, a rotary spike harrow, is an elongated tool with a ground working portion having spikes extending therefrom. A rotary spike harrow is described in U.S. Pat. No. 5,000,270 of L. C. Phillips. The harrow of Phillips is formed of a plurality of interconnected tool elements forming an elongate chain-like structure, termed herein the ground working portion of the harrow. The ends of the ground working portion are connected to a support frame in such a way as to enable the chain-like structure to rotate about its long axis. The harrow generally includes a rotatable bearing assembly, such as a shaft supported in a bearing, to permit rotation of the ground working portion about its long axis.
In previous rotary spike harrows, the rotatable bearing assembly is connected between the ground working portion and the frame. In these harrows, a space measuring about one foot in length is left between the frame and the first, end spikes on the ground working portion. Thus, in the simultaneous use of more than one section of rotary spike harrow for cultivation of large expanses of soil, it is required that the harrow sections be mounted behind the tractor in a tiered in an partially overlapping manner to avoid leaving a strip of uncultivated soil between each adjacent section. In particular, where harrow sections are used in end to end relation, without overlapping, a strip of uncultivated soil is left after a pass of the harrow. The strip corresponds to the space between the ground working portions of adjacent harrows. Additionally in previous harrows, the bearing assemblies are open and, therefore, susceptible to damage by collisions with objects, such as rocks, on the ground surface which is being cultivated.
A harrow bearing assembly has been invented which is relatively resistant to damage during use. The harrow bearing reduces the space between the ground working portion of the harrow and the frame on which the ground working portion is mounted.
In accordance with a broad aspect of the present invention, there is provided a bearing assembly comprising a housing, a shaft supported within the housing and having an end extending through an opening in an end of the housing, a bearing disposed between the shaft and the housing to permit rotation of the shaft within the housing; and a harrow ground working portion engaging means positioned on the housing either a) diametrically adjacent the bearing or b) between the bearing and the end of the shaft extending from the housing.
The bearing can be any suitable means for supporting and permitting rotation of the shaft relative to the housing, as would be understood by a person skilled in the art. In one embodiment, the bearing includes at least one race of ball bearings in a standard bearing ring. The bearing is selected to withstand the forces applied thereto when connected to a harrow. To enhance the accommodation of lateral forces on the shaft, the bearing preferably includes at least one bearing, such as a tapered roller bearing, suited for accommodating such forces. The bearing is disposed within the housing. Preferably, the housing is sealed to prevent debris from entering the housing and from coming into contact with the bearing means.
The shaft is selected to withstand the forces applied thereto when used in a harrow. Preferably, the shaft is formed of steel. In one embodiment, an end of the shaft opposite the housing is formed, for example, to include an eye, for attachment to a harrow support frame. The eye can be formed from the material of the shaft or can be formed separately and attached thereto. In another embodiment, the shaft is formed integral with a harrow support frame.
The harrow ground working portion engaging means are any suitable means for retaining the ground working portion of a harrow thereon. The ground working portion engaging means are positioned on the housing of the bearing means. The engaging means are formed integral with (ie. as by casting), or alternatively secured (i.e. as by welding), to the housing. The engaging means can be any suitable means provided that they are positioned in one of a) diametrically adjacent the bearing and b) between the bearing and the end of the shaft extending from the housing. In other words, the engaging means are positioned to engage the ground working portion of the harrow such that the ground working portion extends to overlap with at least a portion of the bearing. This arrangement shortens the length of the harrow over previous harrows, since the bearing and a portion of the housing is positioned within the length of the ground working portion. The arrangement also provides protection for the more delicate components, including the housing and the bearing, of the bearing assembly. The components of the ground working portion are more durable than the bearing housing and the bearing contained therein and, therefore, are more able to accommodate collisions with objects without critical damage thereto.
In one embodiment, the harrow ground working portion engaging means is a weld between the ground working portion and the housing. In another embodiment, the harrow ground working portion engaging means is a flange about the open end of the housing including, for example, protrusions or hooks for engaging an end of the harrow, apertures for accepting fasteners such as, for example, wire or bolts connecting between the bearing housing and the ground working portion of the harrow or other means.
The bearing assembly is particularly suited for use with a rotary spike harrow of the type having a ground working portion which includes a plurality of interconnected tool elements. Each tool element is formed to be substantially U-shaped and includes a pair of spikes extending from a loop portion which spans the spikes. The ground working portion of the harrow is formed as a series of groups of tool elements. Each group includes at least two tool elements arranged to define a central space therebetween. Each group of tool elements is releasably hooked to the adjacent group to form flexible connections therebetween. Tensioning the harrow along its longitudinal axis ensures that the groups of tool elements remain hooked together. When under tension, the arms of the tool elements extend out to form the ground working spikes of the harrow. Thus, preferably, the bearing assembly of the present invention is formed to engage this ground working portion of the harrow and has harrow ground working portion engaging means including hooks to engage the loop portions of the tool elements, apertures for accepting bolts to engage the spikes of the tool elements or a combination of hooks and apertures.
In accordance with another broad aspect of the present invention, there is provided a harrow comprising: a ground working portion including a plurality of tool elements arranged in a series of groups, each group of tool elements being hooked together with its adjacent group of tool elements to form flexible connections between the groups, each group formed of at least two tool elements disposed to define a central space therebetween and each tool element including a loop portion and a pair of spikes extending from the loop portion; a bearing assembly engaged at each end of the ground working portion, at least one bearing assembly including a housing, a shaft supported within the housing and having an end extending through an opening in an end of the housing, a bearing disposed between the shaft and the housing to permit rotation of the shaft within the housing, the at least one bearing assembly being engaged to the end of the ground working portion such that the bearing is positioned within the central group of tool elements and the shaft extends out from the central space at the end of the ground working portion.
The harrow can be mounted onto a frame. The shafts of the bearing assemblies are secured onto the frame in any suitable way, such that the ground working portion can rotate with the bearing housing about the shafts. The frame is selected to maintain the ground working portion under tension.